Madam C.J. Walker's early years are largely hidden from history, so Beverly Lowry had to be a detective. The sleuthing itself is a key part of the work.

Of all the disciplines of writing, biography is commonly regarded as the most black and white. What is there to interpret in the records of a lifetime? How can conjecture arise out of fact? Such an impression is only heightened by the intimidating size of so many biographies, their bibliographies and citations, their weight and heft.

The truth, however, is that in a postmodern universe, biography is as subjective as any endeavor, as much a matter of the connection between author and subject, of trying to forge a passage into another life. "The living soul is wily," notes Beverly Lowry in "Her Dream of Dreams: The Triumph of Madam C.J. Walker," "and the heart eludes discovery. And we will never know it all."

Reached by phone in Fairfax, Va., where she directs the creative nonfiction program at George Mason University, Lowry elaborates on this sensibility. "I looked at a lot of biographies," she says. "They involve a good deal of speculation even when we know things. Even the sources are subjective, which means we're always dealing with a biographer's assertion of events. If you read closely, you can see where the research ends and the writer enters the work."

The idea that research only takes us so far, that at a certain point we must yield to imagination, is particularly resonant when it comes to "Her Dream of Dreams" because this is a biography where speculation is essential, in both content and style. Although she has been written about before, Madam C.J. Walker remains an indistinct figure in American history, despite having been an early African American entrepreneur and role model, the first woman of any heritage to become a self-made millionaire in the U.S.

While Lowry uncovered an array of records and promotional information documenting Madam Walker's business, virtually no material exists on her early life. What we know is that she was born Sarah Breedlove in 1867 in a tiny Mississippi River hamlet in Louisiana, that she built her fortune selling hair products to black women, and at her death in 1919 owned a townhouse in Harlem and a Westchester estate. But there are few records, no birth certificate or census reports -- nothing, in fact, until around 1900, when she was already 33 years old.

This means that, as a biographer, Lowry faced enormous responsibility and enormous freedom, the need to re-create Walker's youth in a way that seems believable, while still acknowledging all she could not know. "I had to build her character out of context," Lowry says. "In fiction, you do that intuitively, but here, it required a creative leap."

When Lowry talks about fiction, she is on familiar ground. The author of six novels and one previous work of nonfiction -- "Crossed Over," about executed Texas murderer Karla Faye Tucker -- she brings a narrative approach to her portrayal of Walker, a novelist's recognition of the way a life, like a story, develops and arcs over time.

It was, in fact, through the filter of fiction that Lowry first "met" her subject; in the early 1990s, she was approached by the family of "Roots" author Alex Haley, who had been planning a novel about Madam Walker before he died. Haley's executors asked if Lowry might want to take up the project, but although the character compelled her, she decided fiction was not the way to go.

"It seemed impossible," she remembers. "There were too many holes. But I was fascinated, and I wanted to learn more. It was like a mystery, the idea of this woman emerging out of nowhere, so I just blundered forward. It was a little nuts. I had no training in historical research, in how to arrange the data.

"I started going to courthouses and looking up records, seeing where they led. Almost everything I've ever written is about a woman moving against the odds, which is at the heart of this story also. And because information was so scarce, I had no choice but to put the emphasis on process rather than end product. I wanted to be part of that process, which meant I had to become part of the story myself."

As it turns out, Lowry's engagement in "Her Dream of Dreams" is a key part of the story. Rather than be put off by a lack of information, she uses whatever details are available to imagine Walker and her world. "Most accounts of Madam Walker's life," she writes in one instance, "state that she came to Vicksburg [Mississippi] when she was about 10 years old, with her sister Louvenia, who was about 14; and that Louvenia married a man named Powell and the three of them lived together, but that Sarah's brother-in-law was cruel to her and so, at 14, she married Jeff -- or Moses -- McWilliams. Some of this story is doubtless true."